diff --git a/layout/reftests/table-background/reftest.list b/layout/reftests/table-background/reftest.list
index af14df7ef5b..518c566f48a 100644
--- a/layout/reftests/table-background/reftest.list
+++ b/layout/reftests/table-background/reftest.list
@@ -40,14 +40,14 @@
 == border-collapse-table-row.html border-collapse-table-row-ref.html
 == border-collapse-table.html border-collapse-table-ref.html
 == border-collapse-opacity-table-cell.html border-collapse-opacity-table-cell-ref.html
-fails == border-collapse-opacity-table-column-group.html border-collapse-opacity-table-column-group-ref.html
-fails == border-collapse-opacity-table-column.html border-collapse-opacity-table-column-ref.html
+fails == border-collapse-opacity-table-column-group.html border-collapse-opacity-table-column-group-ref.html # bug 424274
+fails == border-collapse-opacity-table-column.html border-collapse-opacity-table-column-ref.html # bug 424274
 == border-collapse-opacity-table-row-group.html border-collapse-opacity-table-row-group-ref.html
 == border-collapse-opacity-table-row.html border-collapse-opacity-table-row-ref.html
 == border-collapse-opacity-table.html border-collapse-opacity-table-ref.html
 == border-separate-opacity-table-cell.html border-separate-opacity-table-cell-ref.html
-fails == border-separate-opacity-table-column-group.html border-separate-opacity-table-column-group-ref.html
-fails == border-separate-opacity-table-column.html border-separate-opacity-table-column-ref.html
+fails == border-separate-opacity-table-column-group.html border-separate-opacity-table-column-group-ref.html # bug 424274
+fails == border-separate-opacity-table-column.html border-separate-opacity-table-column-ref.html # bug 424274
 == border-separate-opacity-table-row-group.html border-separate-opacity-table-row-group-ref.html
 == border-separate-opacity-table-row.html border-separate-opacity-table-row-ref.html
 == border-separate-opacity-table.html border-separate-opacity-table-ref.html